sealing a new transom

[woolleyhatter]

Dear fonts of all knowledge

I'm fitting a new transom to my Folkboat and am at odds what to seal it with.
Some suggest Sikaflex 291, but having read a little about this it may not be the answer.

Any suggestions?

Many thanks

 

[Seanick]

Arbomast Butyl Rubber, or any non-setting mastic'
Not Sika, Silicon, 3M5200, oil based mastics or putty,